I pulled apart my 1921 Peugeot transmission. It's a 3-speed "in-line" shifter. Since the car didn't run when I got it, I can't tell how well the trans works. It seems to shift through all the gears OK. There are no obvious horrors, missing teeth, burning, cracks etc. but there is wear to the gears; some cutting along the edges, general wear, and shavings in the oil. How do I judge if any gears need replacement or repair?

Phil Jamison
PA

Hello,
Hobbed gear teeth generally are cut with .003" to .004"
backlash, assuming the shaft bearings/ bushings are still
whithin their wear limits...
Thanks,
Joe Kieliszek
'11 Buick model 14 (still fixin' it up)

Is "hobbed" the term for the fit of any gear teeth?

Phil Jamison
PA

Hello,
A gear hob refers to the cutter, usually used for productio
gear cutting. All gear cutters are made for specific gear
tooth size and # of gear teeth of the gear, pitch angle
of the gear tooth, etc.
Thanks,
Joe

I took the transmission apart. Here's a photo of some of the gear wear. I decided to fix this gear cluster, which looks pretty bad to me; almost 50% tooth wear. Is there some way to repair tooth wear like this with weld, or would an entirely new gear have to be cut?



Phil Jamison
PA

Hi Phil,
My gut feeling would be to go with either an entirely new gear blank of either 4140 / 4340 steel if you don't have
any internal splines in the gear bore. if there is a splined bore, the old gear teeth could be turned off (following annealing of the gear)to about a half inch deeper than the lowest point of the tooth. A couple of rings could be machined and sweated on (with a .002 to .003 interferance fit). These than would be welded from the outer sides at the split line (a weld champher on the mating surfaces would be first machined). The new teeth could then be cut in.
Just my thoughts,
Thanks, Joe

I found a machinist who specializes in gears. He said he could make my Peugeot gear, but heat-treating would be needed. First, the gear is cut close to its final shape, then it is sent to be annealed. This "relaxes" the metal to remove stress. The gear is then cut to the final shape and heat-treated to harden the steel fully. I'm hoping for the best.

Phil Jamison
PA

Hi Phil,
Sounds like a plan; after going through an effort like
this, its just a better idea going with freshly made replacements..
Thanks,
Joe

The first gear guy sent the gear back without explanation. Too weird for him, I guess. Today, I brought it to Chalmers & Kubeck in Aston, PA. They have an impressive gear shop (a factory, actually). I got a tour from the Senior Gear Engineer. I expected to see only computerized machinery, but most everything was "hand-controlled". The blank sits on a table and a spinning cutter moves up and down, slowly forming the teeth. They have drawers full of these cutters, which can cost $4,000 each. The engineer had actually guessed my tooth pitch from the photos I sent! My puny gear looked out of place in this huge shop, but I was told they could make it. They even seemed rather interested in the job. Not many 1921 Peugeot jobs come their way, I guess. I have only to await the estimate. I hope I'm not too shocked!

Phil Jamison

Hi Phil,
No cheap way around gears; I paid $780 bucks for a Starret
gear tooth venier several years back....
Thanks,
Joe